The invention relates to the labeling of objects by the use of heat to transfer design prints from a carrier to objects being labeled.
In heat transfer labeling, a design print overlying a release layer on a carrier is brought into contact with an object to be labeled. When heat is applied to the carrier, the release layer becomes molten and permits the design print to be transferred to the object.
In the typical heat transfer label, as exemplified by U.S. Pat. No. 3,616,015, which issued Oct. 26, 1971, the release layer is a coating of wax on the carrier and the design print is in a transfer layer that is printed on the wax coating. With such a label, the application of heat during the transfer process causes a film of wax to be deposited over the entire region where the carrier is in contact with the object being labeled. The deposited film is of random configuration and is frequently much larger than the design print.
Although the wax film is transparent and generally not noticeable by casual observation, under certain lighting conditions the film is viewable and can present an objectionable appearance. The resulting film can be regarded as an expanded, irregular "halo" that surrounds the design print. Not only can the irregular halo present an objectionable appearance, it represents a wastage of material. Moreover, because of the tendency of the wax to penetrate the carrier material used in ordinary heat transfer labeling, a substantial amount of wax material is needed to form the transfer coating.
Accordingly, it is an object of the invention to facilitate the heat transfer labeling of objects. Another object is to improve the appearance of heat transfer labels. A related object is to eliminate the enlarged, irregular halo often encountered in heat transfer labeling. Still another object is to economize on the amount of material needed for the release layer in the heat transfer labeling of objects.
A further object of the invention is to achieve an enhanced appearance of the design print where the amount of material needed for the release layer has been economized.
A still further object is to facilitate the adhesion of the transfer layer to a surface being labeled where the amount of material needed for the release has been economized and the surface exhibits a high degree of irregularities.
Yet another object of the invention is to adapt relatively high temperature transfer materials for use at lower transfer temperatures where the amount of material needed for the release has been economized.
Still another object of the invention is to facilitate the application of the transfer layer with respect to the release layer where the amount of material needed for the release has been economized.